Cystoisosporiasis also known as Isosporiasis is an uncommon intestinal disease caused by parasitic infection of Cystoisospora belli. This disease is common in subtropical and tropical regions of the world. The parasite spreads by ingesting contaminated food or water, the most common symptom includes watery diarrhoea, which may be associated with abdominal pain, cramping, anorexia, nausea, vomiting, and low-grade fever. If untreated, people with weak immune systems, such as people with AIDS, may be at higher risk for severe or prolonged illness. The diagnosis of cystoisosporiasis is usually made by identifying oocysts in stool wet mounts or stained fecal smears.
Geographical distribution of Cystoisosporiasis is Worldwide, especially in tropical and subtropical areas. Infection occurs in immunodepressed individuals, and outbreaks have been reported in institutionalized groups in the Japan.
Cystoisosporiasis can be treated with the sulfa drugs like trimethoprim-sulfamethoxazole. For adults, the daily dose of pyrimethamine is in the range of 50 to 75 mg. This dose is given orally, either once a day or divided into 2 separate doses. Clinical management includes fluid and electrolyte support for dehydrated patients and nutritional supplementation for malnourished patients. If symptoms worsen or persist despite approximately 5 to 7 days of TMP-SMX therapy, the possibilities of noncompliance, malabsorption, and concurrent infections/enteropathies should be considered; the TMP-SMX regimen (daily dose, duration, and mode of administration) also should be reevaluated.
Some of the major researches on Cystoisosporiasis are Molecular Diagnosis of Cystoisosporiasis Using Extended-Range PCR Screening, Ultrastructural aspects of Cystoisospora belli (syn. Isospora belli) in continuous cell lines.